1. Field of Invention
This invention relates to safely sampling urine from the urinary bladder.
2. Description of Prior Art
Physicians order a vast number of urine tests every day. Many of these tests are routine and most seek information of chemical or of hormonal nature. Such tests can reliably be performed on voided urine specimens. The urine is simply gathered in an open cup. Patients can do their own specimen collecting and sterile precautions are unnecessary. A few contaminating bacteria will not affect the test results.
But when the problem of managing urinary infection arises, voided specimens become unreliable. Bacterial organisms living in the genital area will contaminate voided urine specimens and lead to erroneous culture findings. Wrong organisms are treated; false antibiotic sensitivity studies are obtained; and uninfected patients are unnecessarily treated.
Thus the bacteriologic study of urine requires a different method of urine sampling.
Originally and even in practice today many suspected infections of the urinary tract are studied by passing a sterile straight hollow tube (catheter) directly into the bladder to obtain urine. Bacterial contamination of urine specimens can be avoided by the use of a catheter. With some basic skill and a little experience, one can obtain an uncontaminated urine sample using this straight catheter method.
Unfortunately, as the catheter advances, it slides through a zone of bacterial contamination in the distal urethra before entering the bladder. The catheter then carries bacteria into the bladder where seeding occurs. Patients who did not have bladder infection will often develop bladder infection following and as a result of straight catheterization.
Recently inventors created several variations of the catheter which are intended to prevent bladder seeding with organisms from the lower urethra. U.S. Pat. No. 3,908,663 A dated Sep. 30, 1975 to N. F. Viek, and International patent WO 92/21399A dated Dec. 10, 1992 to R. Feliziani and M. L. Jake use a progressively unrolling separate membrane to isolate urethral walls from the advancing catheter. Similarly U.S. Pat. No. 4,106,659 dated Aug. 29, 1978 to D. Sheriden describes an unrolling separate membrane. Sheriden's membrane is unrolled by externally applied fluid pressure.
While membrane catheters do have the potential to avoid bladder contamination, they have not received general acceptance. These devices are complicated to use and expensive to manufacture. They require training and technical skills which are not always available in the working clinical laboratory.
Another variation of the catheter intended to prevent bladder seeding was patented by V. F. Viek (U.S. Pat. No. 3,908,635 dated Sep. 30, 1975). He describes a simplified catheter comprising a disc with an opening and attached flexible tube which passes through the opening and "everts" into the urethra.
This design seems preferable to the complexity of a separate membrane. Because the advancing tube forms its own encasement, the everting feature substitutes for a separate membrane. And nowhere does a sliding surface contact a contaminated area.
Clearly Viek's simplified catheter contains a good basic idea for safely traversing the urethral canal. Yet this simplified design functions poorly as a clinical tool and it suffers from a number of disadvantages:
(a) The disc is too small to adequately control the device. PA1 (b) Placing the disc against the skin of the perineum conceals the opening to the urethra, requiring blind catheterization. PA1 (c) Pressing the disc against the perineum compresses and traps folds of urethral mucosa making penetration difficult and sometimes painful. PA1 (d) The urine specimen dribbles uncontrolled from the catheter and is subject to spillage and contamination. PA1 (e) Coughing or laughing by the patient will lead to uncontrollable spraying of urine. PA1 (f) A sterile procedure tray of equipment is needed to supplement this catheter. PA1 (g) An operator trained in sterile technique is needed to supplement this catheter. PA1 (a) to provide a well supported and controlled device allowing incremental changes of catheter direction, pressure, and rate of penetration; PA1 (b) to gently separate mucosal folds at the urethral opening and permit easy penetration by the catheter; PA1 (c) to prevent excessive penetration of the urethra without blocking visualization of the meatus; PA1 (d) to collect urine without bacterial contamination of the specimen; PA1 (e) to collect urine without bacterial contamination of the bladder; PA1 (f) to avoid spillage by use of a controlled drainage tube; PA1 (g) to provide a safe means for introducing medications into the bladder; PA1 (h) to decrease the level of training required for urine sampling; PA1 (i) to decrease the amount of equipment required for urine sampling; PA1 (j) to decrease the cost of urine sampling.